LM94023 1.5V, micro SMD, Dual-Gain Analog Temperature Sensor with Class AB Output General Description The LM94023 is a precision analog output CMOS integratedcircuit temperature sensor that operates at a supply voltage as low as 1.5 Volts. Available in the very small four-bump microSMD 0.8mm x 0.8mm) the LM94023 occupies very little board area. A class-AB output structure gives the LM94023 strong output source and sink current capability for driving heavy loads, making it well suited to source the input of a sample-and-hold analog-to-digital converter with its transient load requirements, This generally means the LM94023 can be used without external components, like resistors and buffers, on the output. While operating over the wide temperature range of −50°C to +150°C, the LM94023 delivers an output voltage that is inversely porportional to measured temperature. The LM94023's low supply current makes it ideal for battery-powered systems as well as general temperature sensing applications. A Gain Select (GS) pin sets the gain of the temperature-tovoltage output transfer function. Either of two slopes are selectable: −5.5 mV/°C (GS=0) or −8.2 mV/°C (GS=1). In the lowest gain configuration, the LM94023 can operate with a 1.5V supply while measuring temperature over the full −50°C to +150°C operating range. Tying GS high causes the transfer function to have the largest gain for maximum temperature sensitivity. The gain-select inputs can be tied directly to VDD or Ground without any pull-up or pull-down resistors, reducing component count and board area. These inputs can also be driven by logic signals allowing the system to optimize the gain during operation or system diagnostics. Applications ■ ■ ■ ■ ■ Battery Management Automotive Disk Drives Games Appliances Features ■ ■ ■ ■ ■ ■ ■ ■ Low 1.5V operation Push-pull output with 50µA source current capability Two selectable gains Very accurate over wide temperature range of −50°C to +150°C Low quiescent current Output is short-circuit protected Extremely small microSMD package Footprint compatible with the industry-standard LM20 temperature sensor Key Specifications ■ Supply Voltage ■ Supply Current ■ Output Drive ■ Temperature Accuracy 1.5V to 5.5V 5.4 μA (typ) ±50 μA 20°C to 40°C -50°C to 70°C -50°C to 90°C -50°C to 150°C ±1.5°C ±1.8°C ±2.1°C ±2.7°C ■ Operating ■ Cell phones ■ Wireless Transceivers Temperature Connection Diagram −50°C to 150°C Typical Transfer Characteristic micro SMD Output Voltage vs Temperature 30075001 Top View See NS Package Number TMD04AAA 30075024 © 2008 National Semiconductor Corporation 300750 www.national.com LM94023 1.5V, micro SMD, Dual-Gain Analog Temperature Sensor with Class AB Output September 10, 2008 LM94023 Typical Application Full-Range Celsius Temperature Sensor (−50°C to +150°C) Operating from a Single Battery Cell 30075002 Ordering Information Order Number Temperature Accuracy NS Package Number Device Marking LM94023BITME ±1.5°C to ±2.7°C TMD04AAA Date Code 250 Units on Tape and Reel LM94023BITMX ±1.5°C to ±2.7°C TMD04AAA Date Code 3000 Units on Tape and Reel Transport Media Pin Descriptions Label Pin Number Type Equivalent Circuit Function GS A1 Logic Input Gain Select - Input for selecting the slope of the analog output response GND A2 Ground Power Supply Ground VOUT B1 Analog Output Outputs a voltage which is inversely proportional to temperature VDD B2 Power Positive Supply Voltage www.national.com 2 Supply Voltage Voltage at Output Pin Output Current Voltage at GS Input Pin Input Current at any pin (Note 2) Storage Temperature Maximum Junction Temperature (TJMAX) ESD Susceptibility (Note 3): Human Body Model −0.3V to +6.0V −0.3V to (VDD + 0.3V) ±7 mA −0.3V to +6.0V 5 mA −65°C to +150°C Operating Ratings (Note 1) Specified Temperature Range: LM94023 TMIN ≤ TA ≤ TMAX −50°C ≤ TA ≤ +150°C Supply Voltage Range (VDD) +150°C +1.5 V to +5.5 V Thermal Resistance (θJA) LM94023BITME, LM94023BITMX 2500V 250V 122.6°C/W Accuracy Characteristics These limits do not include DC load regulation. These stated accuracy limits are with reference to the values in the LM94023 Transfer Table. Parameter Conditions Temperature Error GS=0 (Note 8) GS=1 Limits (Note 7) Units (Limit) TA = +20°C to +40°C; VDD = 1.5V to 5.5V ±1.5 °C (max) TA = +0°C to +70°C; VDD = 1.5V to 5.5V ±1.8 °C (max) TA = +0°C to +90°C; VDD = 1.5V to 5.5V ±2.1 °C (max) TA = +0°C to +120°C; VDD = 1.5V to 5.5V ±2.4 °C (max) TA = +0°C to +150°C; VDD = 1.5V to 5.5V ±2.7 °C (max) TA = −50°C to +0°C; VDD = 1.6V to 5.5V ±1.8 °C (max) TA = +20°C to +40°C; VDD = 1.8V to 5.5V ±1.5 °C (max) TA = +0°C to +70°C; VDD = 1.9V to 5.5V ±1.8 °C (max) TA = +0°C to +90°C; VDD = 1.9V to 5.5V ±2.1 °C (max) TA = +0°C to +120°C; VDD = 1.9V to 5.5V ±2.4 °C (max) TA = +0°C to +150°C; VDD = 1.9V to 5.5V ±2.7 °C (max) TA = −50°C to +0°C; VDD = 2.3V to 5.5V ±1.8 °C (max) 3 www.national.com LM94023 Machine Model Soldering process must comply with National's Reflow Temperature Profile specifications. Refer to www.national.com/packaging. (Note 4) Absolute Maximum Ratings (Note 1) LM94023 Electrical Characteristics Unless otherwise noted, these specifications apply for +VDD = +1.5V to +5.5V. Boldface limits apply for TA = TJ = TMIN to TMAX ; all other limits TA = TJ = 25°C. Symbol Parameter Sensor Gain Load Regulation (Note 10) Conditions Typical (Note 6) Limits (Note 7) Units (Limit) GS = 0 -5.5 mV/°C GS = 1 -8.2 mV/°C 1.5V ≤ VDD < 5.5V Source ≤ 50 μA, -0.22 -1 mV (max) Sink ≤ 50 μA, 0.26 1 mV (max) (VDD - VOUT) ≥ 200mV VOUT ≥ 200mV Line Regulation (Note 13) IS Supply Current μV/V 200 TA = +30°C to +150°C, 5.4 8.1 μA (max) TA = -50°C to +150°C, 5.4 9 μA (max) 1.9 ms (max) (VDD - VOUT) ≥ 100mV (VDD - VOUT) ≥ 100mV CL Output Load Capacitance Power-on Time (Note 11) 1100 CL= 0 pF to 1100 pF 0.7 pF (max) VIH GS1 and GS0 Input Logic "1" Threshold Voltage VDD- 0.5V V (min) VIL GS1 and GS0 Input Logic "0" Threshold Voltage 0.5 V (max) IIH Logic "1" Input Current (Note 12) 0.001 1 μA (max) IIL Logic "0" Input Current (Note 12) 0.001 1 μA (max) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions. Note 2: When the input voltage (VI) at any pin exceeds power supplies (VI < GND or VI > V+), the current at that pin should be limited to 5 mA. Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. Note 4: Reflow temperature profiles are different for lead-free and non-lead-free packages. Note 5: The junction to ambient thermal resistance (θJA) is specified without a heat sink in still air. Note 6: Typicals are at TJ = TA = 25°C and represent most likely parametric norm. Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 8: Accuracy is defined as the error between the measured and reference output voltages, tabulated in the Transfer Table at the specified conditions of supply gain setting, voltage, and temperature (expressed in °C). Accuracy limits include line regulation within the specified conditions. Accuracy limits do not include load regulation; they assume no DC load. Note 9: Changes in output due to self heating can be computed by multiplying the internal dissipation by the thermal resistance. Note 10: Source currents are flowing out of the LM94023. Sink currents are flowing into the LM94023. Note 11: Guaranteed by design. Note 12: The input current is leakage only and is highest at high temperature. It is typically only 0.001µA. The 1µA limit is solely based on a testing limitation and does not reflect the actual performance of the part. Note 13: Line regulation (DC) is calculated by subtracting the output voltage at the highest supply voltage from the output voltage at the lowest supply voltage. The typical DC line regulation specification does not include the output voltage shift discussed in Section 5.0. www.national.com 4 Temperature Error vs. Temperature Minimum Operating Temperature vs. Supply Voltage 30075007 30075006 Supply Current vs. Temperature Supply Current vs. Supply Voltage 30075004 30075005 5 www.national.com LM94023 Typical Performance Characteristics LM94023 Load Regulation, Sourcing Current Load Regulation, Sinking Current 30075040 30075041 Line Regulation: Change in Vout vs. Overhead Voltage Supply-Noise Gain vs. Frequency 30075042 www.national.com 30075043 6 Line Regulation: Output Voltage vs. Supply Voltage Gain Select = 1 30075034 30075035 7 www.national.com LM94023 LIne Regulation: Output Voltage vs. Supply Voltage Gain Select = 0 LM94023 1.0 LM94023 Transfer Function Temperature (°C) GS = 0 (mV) GS = 1 (mV) -13 1104 1671 -12 1098 1663 -11 1093 1656 -10 1088 1648 -9 1082 1639 -8 1077 1631 -7 1072 1623 LM94023 Temperature-Voltage Transfer Table -6 1066 1615 -5 1061 1607 The output voltages in this table apply for VDD = 5V. Temperature GS = 0 GS = 1 (°C) (mV) (mV) -4 1055 1599 -3 1050 1591 -2 1044 1583 -50 1299 1955 -1 1039 1575 -49 1294 1949 0 1034 1567 -48 1289 1942 1 1028 1559 -47 1284 1935 2 1023 1551 -46 1278 1928 3 1017 1543 -45 1273 1921 4 1012 1535 -44 1268 1915 5 1007 1527 -43 1263 1908 6 1001 1519 -42 1257 1900 7 996 1511 -41 1252 1892 8 990 1502 -40 1247 1885 9 985 1494 -39 1242 1877 10 980 1486 -38 1236 1869 11 974 1478 -37 1231 1861 12 969 1470 -36 1226 1853 13 963 1462 -35 1221 1845 14 958 1454 -34 1215 1838 15 952 1446 -33 1210 1830 16 947 1438 -32 1205 1822 17 941 1430 -31 1200 1814 18 936 1421 -30 1194 1806 19 931 1413 -29 1189 1798 20 925 1405 -28 1184 1790 21 920 1397 -27 1178 1783 22 914 1389 -26 1173 1775 23 909 1381 -25 1168 1767 24 903 1373 -24 1162 1759 25 898 1365 -23 1157 1751 26 892 1356 -22 1152 1743 27 887 1348 -21 1146 1735 28 882 1340 -20 1141 1727 29 876 1332 -19 1136 1719 30 871 1324 -18 1130 1711 31 865 1316 -17 1125 1703 32 860 1308 -16 1120 1695 33 854 1299 -15 1114 1687 34 849 1291 -14 1109 1679 35 843 1283 The LM94023 has two selectable gains, selected by the Gain Select (GS) input pin. The output voltage for each gain, across the complete operating temperature range is shown in the LM94023 Transfer Table, below. This table is the reference from which the LM94023 accuracy specifications (listed in the Electrical Characteristics section) are determined. This table can be used, for example, in a host processor look-up table. A file containing this data is available for download at www.national.com/appinfo/tempsensors. www.national.com 8 GS = 0 (mV) GS = 1 (mV) Temperature (°C) GS = 0 (mV) GS = 1 (mV) 36 838 1275 85 562 865 37 832 1267 86 557 856 38 827 1258 87 551 848 39 821 1250 88 545 839 40 816 1242 89 539 831 41 810 1234 90 534 822 42 804 1225 91 528 814 43 799 1217 92 522 805 44 793 1209 93 517 797 45 788 1201 94 511 788 46 782 1192 95 505 779 47 777 1184 96 499 771 48 771 1176 97 494 762 49 766 1167 98 488 754 50 760 1159 99 482 745 51 754 1151 100 476 737 52 749 1143 101 471 728 53 743 1134 102 465 720 54 738 1126 103 459 711 55 732 1118 104 453 702 56 726 1109 105 448 694 57 721 1101 106 442 685 58 715 1093 107 436 677 59 710 1084 108 430 668 60 704 1076 109 425 660 61 698 1067 110 419 651 62 693 1059 111 413 642 63 687 1051 112 407 634 64 681 1042 113 401 625 65 676 1034 114 396 617 66 670 1025 115 390 608 67 664 1017 116 384 599 68 659 1008 117 378 591 69 653 1000 118 372 582 70 647 991 119 367 573 71 642 983 120 361 565 72 636 974 121 355 556 73 630 966 122 349 547 74 625 957 123 343 539 75 619 949 124 337 530 76 613 941 125 332 521 77 608 932 126 326 513 78 602 924 127 320 504 79 596 915 128 314 495 80 591 907 129 308 487 81 585 898 130 302 478 82 579 890 131 296 469 83 574 881 132 291 460 84 568 873 133 285 452 9 LM94023 Temperature (°C) www.national.com LM94023 Temperature (°C) GS = 0 (mV) GS = 1 (mV) 134 279 443 135 273 434 136 267 425 137 261 416 138 255 408 139 249 399 140 243 390 141 237 381 142 231 372 143 225 363 144 219 354 145 213 346 146 207 337 147 201 328 148 195 319 149 189 310 150 183 301 sired temperature range from the Table using the two-point equation: Where V is in mV, T is in °C, T1 and V1 are the coordinates of the lowest temperature, T2 and V2 are the coordinates of the highest temperature. For example, if we want to determine the equation of a line with the Gain Setting at GS1 = 0 and GS0 = 0, over a temperature range of 20°C to 50°C, we would proceed as follows: Although the LM94023 is very linear, its response does have a slight downward parabolic shape. This shape is very accurately reflected in the LM94023 Transfer Table. For a linear approximation, a line can easily be calculated over the de- www.national.com Using this method of linear approximation, the transfer function can be approximated for one or more temperature ranges of interest. 10 For operation in very noisy environments, some bypass capacitance should be present on the supply within approximately 2 inches of the LM94023. The LM94023 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be glued or cemented to a surface. To ensure good thermal conductivity, the backside of the LM94023 die is directly attached to the GND pin (Pin 2). The temperatures of the lands and traces to the other leads of the LM94023 will also affect the temperature reading. Alternatively, the LM94023 can be mounted inside a sealedend metal tube, and can then be dipped into a bath or screwed into a threaded hole in a tank. As with any IC, the LM94023 and accompanying wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold temperatures where condensation can occur. If moisture creates a short circuit from the output to ground or VDD, the output from the LM94023 will not be correct. Printed-circuit coatings are often used to ensure that moisture cannot corrode the leads or circuit traces. The thermal resistance junction to ambient (θJA) is the parameter used to calculate the rise of a device junction temperature due to its power dissipation. The equation used to calculate the rise in the LM94023's die temperature is 4.0 Capacitive Loads The LM94023 handles capacitive loading well. In an extremely noisy environment, or when driving a switched sampling input on an ADC, it may be necessary to add some filtering to minimize noise coupling. Without any precautions, the LM94023 can drive a capacitive load less than or equal to 1100 pF as shown in Figure 2. For capacitive loads greater than 1100 pF, a series resistor may be required on the output, as shown in Figure 3. 30075015 FIGURE 2. LM94023 No Decoupling Required for Capacitive Loads Less than 1100 pF. where TA is the ambient temperature, IQ is the quiescent current, ILis the load current on the output, and VO is the output voltage. For example, in an application where TA = 30 °C, VDD = 5 V, IDD = 9 μA, Gain Select = 11, VOUT = 2.231 mV, and IL = 2 μA, the junction temperature would be 30.021 °C, showing a self-heating error of only 0.021°C. Since the LM94023's junction temperature is the actual temperature being measured, care should be taken to minimize the load current that the LM94023 is required to drive. Figure 1 shows the thermal resistance of the LM94023. Device Number LM94023BITME, LM94023BITMX NS Package Number Thermal Resistance (θJA) TMD04AAA 122.6 °C/W 30075033 CLOAD Minimum RS 1.1 nF to 99 nF 3 kΩ 100 nF to 999 nF 1.5 kΩ 1 μF 800 Ω FIGURE 3. LM94023 with series resistor for capacitive Loading greater than 1100 pF. FIGURE 1. LM94023 Thermal Resistance 5.0 Output Voltage Shift 3.0 Output and Noise Considerations The LM94023 is very linear over temperature and supply voltage range. Due to the intrinsic behavior of an NMOS/PMOS rail-to-rail buffer, a slight shift in the output can occur when the supply voltage is ramped over the operating range of the device. The location of the shift is determined by the relative levels of VDD and VOUT. The shift typically occurs when VDD- VOUT = 1.0V. This slight shift (a few millivolts) takes place over a wide change (approximately 200 mV) in VDD or VOUT. Since the shift takes place over a wide temperature change of 5°C to 20°C, VOUT is always monotonic. The accuracy specifications in the Electrical Characteristics table already include this possible shift. A push-pull output gives the LM94023 the ability to sink and source significant current. This is beneficial when, for example, driving dynamic loads like an input stage on an analogto-digital converter (ADC). In these applications the source current is required to quickly charge the input capacitor of the ADC. See the Applications Circuits section for more discussion of this topic. The LM94023 is ideal for this and other applications which require strong source or sink current. The LM94023's supply-noise gain (the ratio of the AC signal on VOUT to the AC signal on VDD) was measured during bench tests. It's typical attenuation is shown in the Typical Performance Characteristics section. A load capacitor on the output can help to filter noise. 11 www.national.com LM94023 2.0 Mounting and Thermal Conductivity LM94023 example, noise coupling on the output line or quantization noise induced by an analog-to-digital converter which may be sampling the LM94023 output). Another application advantage of the digitally selectable gain is the ability to perform dynamic testing of the LM94023 while it is running in a system. By toggling the logic levels of the gain select pin and monitoring the resultant change in the output voltage level, the host system can verify the functionality of the LM94023. 6.0 Selectable Gain for Optimization and In Situ Testing The Gain Select digital inputs can be tied to the rails or can be driven from digital outputs such as microcontroller GPIO pins. In low-supply voltage applications, the ability to reduce the gain to -5.5 mV/°C allows the LM94023 to operate over the full -50 °C to 150 °C range. When a larger supply voltage is present, the gain can be increased as high as -8.2 mV/°C. The larger gain is optimal for reducing the effects of noise (for www.national.com 12 LM94023 7.0 Applications Circuits 30075018 FIGURE 4. Celsius Thermostat 30075019 FIGURE 5. Conserving Power Dissipation with Shutdown 30075028 Most CMOS ADCs found in microcontrollers and ASICs have a sampled data comparator input structure. When the ADC charges the sampling cap, it requires instantaneous charge from the output of the analog source such as the LM94023 temperature sensor and many op amps. This requirement is easily accommodated by the addition of a capacitor (CFILTER). The size of CFILTER depends on the size of the sampling capacitor and the sampling frequency. Since not all ADCs have identical input stages, the charge requirements will vary. This general ADC application is shown as an example only. FIGURE 6. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage 13 www.national.com LM94023 Physical Dimensions inches (millimeters) unless otherwise noted 4-Bump Thin micro SMD Ball Grid Array Package Order Number LM94023BITME and LM94023BITMX NS Package Number TMD04AAA X1 = 0.815 mm X2 = 0.815mm X3 = 0.600mm www.national.com 14 LM94023 Notes 15 www.national.com LM94023 1.5V, micro SMD, Dual-Gain Analog Temperature Sensor with Class AB Output Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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